Classic Chocolate Sheet Cake

Cake:

2 sticks unsalted butter

1 cup water

4 Tbs natural cocoa powder

2 cups flour

2 cups sugar

1 tsp baking soda

1/2 tsp ground cinnamon

1 tsp vanilla extract

1/2 cup buttermilk

2 eggs

Icing:

1 3/4 sticks unsalted butter

4 Tbs natural cocoa powder (heaping)

6 Tbs milk

1 tsp vanilla extract

1 lb powdered sugar, divided

1 cup chopped pecans or walnuts

For cake:

Preheat oven to 350°F. Grease and flour a large rimmed cookie sheet or jelly roll pan. (1/2 sheet size if using a commercial pan.) Set aside.

In a large bowl or an electric mixer, whisk together the flour, sugar, baking soda and cinnamon; set aside.

In a cup stir together the buttermilk, vanilla extract and eggs. Beat slightly to mix and break up eggs; set aside.

In a medium sized saucepan, melt together the butter, water and cocoa powder. Bring to a boil, stirring to incorporate all ingredients. Remove from heat when at a low boil and stir about 30 seconds to cool slightly.

Pour the cocoa mixture into the dry ingredients and stir or beat on low speed to combine and cool slightly. With mixer running, pour in the buttermilk mixture and mix just until combined.

Pour batter into prepared rimmed cookie sheet and smooth with a spatula, covering the entire sheet. Bake in preheated 350°F oven for 20 - 25 minutes, until a toothpick inserted in the center comes out clean.

Set pan on a baker's rack to cool slightly while you prepare the Sheet Cake Icing.

In the same saucepan as you prepared the cocoa mixture for the cake, melt butter and cocoa powder together. When melted and butter starts to foam, cook for 30 seconds, stirring constantly and then remove from the heat. Pour in milk and vanilla extracts; mix well. Stir in the chopped nuts, then stir in the powdered sugar minus 1/2 cup. The hot icing should be a little thin, but if it seems too thin add the remaining 1/2 cup. Stir quickly to combine well and pour the hot icing over the warm cake. Spread the icing with an offset spatula to cover the entire surface. The icing will set very rapidly so work quickly.

Set the cake aside to cool completely before serving.